Supposed to Be Mine
by batman-defeats-all
Summary: It was the shattering of glasses that woke them. The screams of a child, their child, cut through the confused silence that followed, resulting in Mabel desperately jumping out of bed and dashing down the hall, and Bill rushing through the air as he used his magic to throw himself through the air towards their young son's room. Mabill, one-shot


**Sort of a sequel to my last story, "Mine", though is does make sense without it.**

**Mabel is about 25 in this.**

**I do not own Gravity Falls.**

It was the shattering of glasses that woke them.

The screams of a child, _their _child, cut through the confused silence that followed, resulting in Mabel desperately jumping out of bed and dashing down the hall, and Bill rushing through the air as he used his magic to throw himself through the air towards their young son's room.

"William!" he yelled as he burst through the doorway, landing on the carpet floor harshly.

He looked around the room frantically, only for his uncovered eye to glow a bright blue as he saw his son, his beloved little William, struggling to escape the hold of an unknown captor, his little legs kicking out.

"Daddy! Mommy!" he cried out as Mabel slid next to Bill, anger and fear written across her face.

As the attempting kidnapper scrambled to get back to the window he came through, Bill looked into his mind to find his identity, and possibly motives, but he soon recoiled from the mind, scowling in instant recognition.

"Gideon," he growled out, his eye narrowed.

The young man turned towards Bill and Mabel, his eyes brimming with dark madness, a snarl painted on his face, and a sharp knife pointed directly at their son's throat.

"What do you want, Gleeful?" Mabel asked, both her voice and body shaking with rage.

He did not immediately answer, instead taking a few steps back, slowly moving towards the window.

"I asked you a question, Gideon!" she barked, stepping towards him.

"He can't have everythang!" the younger man snapped back, taking a step towards Mabel.

"What is that even supposed to mean?" she threw her arms in the air, already getting pulled into the childish way of speaking she was so used to using with Gideon.

"Ya were suppos'd to be mine!" he replied fiercely.

"... What?" Bill stepped closer to Mabel, both them speaking at the same time.

"Ya were suppos'd to be mine!" he was yelling now. "I saw ya first! Then he came along an' ruined all ma plans! He has everythang I was suppos'd to!"

As he spoke, he waved the knife at Bill, motioning to him.

"That's ridiculous!" Bill exclaimed, aghast, but Gideon ranted on, obviously not caring for the demon's input.

"No matta what I did, ya stayed with him!" his voice cracked as tears sprung up. "He's a demon! Ya choose a _demon _ova me!"

His voice lowered, and the knife was raised to cut slightly into the bottom of William's chin.

Bill's eyes flashed a bright blue as he saw the deep crimson blood of his child slowly drip down the knife, but Mabel put her hand on his shoulder, stopping him from leaping forward.

Pinching the bridge of her nose, Mabel walked toward Gideon, speaking along the way.

"The choice wasn't between a demon and a human, Gideon. It wasn't even close to the simple, or at least not in that way. Bill was the man that I fell in love with after he started to care for me, actually made an effort to become close to my family as well, and apologized for the mistakes of the past. You were the boy I had no choice but to hate after you cared for no one but yourself, tried to hurt people I care about, and constantly made really stupid mistakes," As she finished speaking, she was directly in front of Gideon, who was staring at her with wide eyes.

"It wasn't really a choice between a human or a demon; it was the choice between my prince in disguise and the monster in disguise."

Gideon didn't respond, continuing to stare at her as she gently took a hold of his hand holding the knife and slowly moved it away from her son's throat.

"Is this worth it, Gideon? Do you want to go back to jail?" she asked softly, to receive no response. Deciding to not wait for one, she pulled the sniffling William away from Gideon and into her own arms, and started to turn away from Gideon.

However, she was stopped when his large finger firmly clutched her wrist.

She spun around, her curls tumbling around her, William clutching to her shirt as to not fall from her arms with the movement.

"I don't care. He can't have everythang," he spoke through clenched teeth. Before Mabel or Bill had a chance to reply, he threw the knife in his hand at the approaching demon, hitting him directly in the chest and causing him to tumble down, silvery blood leaking onto the carpet.

"Bill!"

"Daddy!" Mabel and William screamed for their family member as he fell, before the women turned back to Gideon, her eyes full of fiery hatred.

"Do you honestly think you can kill an immortal being?" she asked harshly, her eyes narrowed.

"Of course not," Gideon was scowling as he stepped forward. "But I do know that it will show 'im down, an' that does get rid of the most powerful being in tha room."

As Mabel breathed slowly through her nose, Gideon let go of her arm, grabbing William's instead.

"Ya wanna stay with a demon? Fine, I've given up on that," he spoke softly. "But havin' a filthy half-demon brat? That's a hell of a lot farther than I can allow."

Mabel pulled back at her son, but stopped when Gideon roughly grabbed her face with his open hand.

"I want ya kid. If he can have ya, I hafta get somethin'. Even if the brat resembles your idiot of a brotha, maybe he'll remind me of ya, back when ya were my peach dumplin'."

Mabel stared at him in fear for only a moment. The fear quickly turned to fury, and she swiftly brought her knee up, causing Gideon to let go both of her and William, doubling over.

"I'm sorry, Gideon, but that's not happening." She said as she bent over at the waist slightly, leaning towards his fallen form.

Gideon was about to respond, but his words died in his throat as Bill stepped next to Mabel, putting a hand on her shoulder.

"I called 911 as you were attacking my wife," he said coldly. "I do hope they get here soon, I don't know how long I can control myself."

As sirens were heard outside of the house, Bill raised his eyebrows.

"I guess they had an officer in the area."

Later that night, after a shaking Gideon was carted off by the police and they had explained the attempted kidnapping and assault to an officer, Mabel and Bill lay on the couch in their living room, Mabel clutching the sleeping William to herself tightly.

"We almost lost everything," she eventually said quietly.

"... No."

"How didn't we?"

"I would have never let Gideon take William. I would have tracked him across the world, and any other world he could somehow gain access to, I would get your brother's help, I would do anything to get our son back-"

Mabel sighed, leaning onto Bill's shoulder.

"But for tonight, it was close."

Bill was silent for a moment, before sighing.

"Yeah, it was. But it won't happen again, I promise."

"What is it with you and very large promises?"

"I'm an immortal dream demon, I can do some pretty big things."

"Fair enough."


End file.
